Semiconductor devices and integrated circuits are becoming more highly integrated. As a result, ongoing research seeks to improve characteristics of such devices and circuits, and to secure desirable process advantages. In semiconductor memory devices, as the memory capacity of such devices increases, a critical dimension of patterns in the device is reduced. As a result, photolithography processes for forming a pattern over a wafer are vital components of the semiconductor manufacturing process.
In general, a substrate is patterned and then etched to form active areas. However, at the completion of the etching process, reentrant undercutting has been observed at the interface of the substrate and the pad oxide overlying the substrate, which can lead to undesirable voids during subsequent filling with a dielectric.
This Discussion of the Background section is provided for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this Discussion of the Background section constitute prior art to the present disclosure, and no part of this Discussion of the Background section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.